• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10C
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• pp.959-964
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• 2007

In this paper, for a positive integer M and a prime p such that $M|p^n-1$, families of M-ary sequences using the M-ary Sidel'nikov sequences with period $p^n-1$ are constructed. The family has its maximum magnitude of correlation values upper bounded by $3\sqrt{p^{n}}+6$ and the family size is $(M-1)^2(2^{n-1}-1)$+M-1 for p=2 or $(M-1)^2(p^n-3)/2+M(M-1)/2$ for an odd prime p.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.5
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• pp.223-227
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• 2009

$BaCO_3$ crystals with various morphology were prepared using precipitation, hydrothermal and ligand-assisted methods. An irregular structure of $BaCO_3$ microparticle was obtained by simple precipitation method from $Ba(NO_3)_2$ and $Na_2CO_3$ in aqueous solution. Hexagonal pyramidals of $BaCO_3$ were synthesized using a hydrothermal method between $Ba(NO_3)_2$ and urea. Hexagonal rods of $BaCO_3$ were also synthesized using the ligand-assisted hydrothermal method. The aspect ratio of $BaCO_3$ hexagonal rods was increased with the concentration of ligand.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8C
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• pp.735-741
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• 2005

In this paper, we derived the autocorrelation distributions, i.e., the values and the number of occurrences of each value of the autocorrelation function of Sidel'nikov sequences. The frequency of each autocorrelation value of an M-ary Sidel'nikov sequence is expressed in terms of the cyclotomic numbers of order M. It is also pointed out that the total number of distinct autocorrelation values is dependent not oかy on M but also on the sequence, but always less than or equal to ($\frac{M}{2}$)+1.

• Journal of the Korean Vacuum Society
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• v.15 no.5
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• pp.506-511
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• 2006

ZnO nanorods were prepared by the hydrothermal reaction of a solution containing $Zn(NO_3)_2{\cdot}6H_2O$, NaOH, cyclohexylamine, ethanol and water, and their $NO_2$ and CO sensing behaviors were investigated. By the control of water concentration in solution, the morphology and agglomeration of ZnO nanorods could be manipulated, which is associated with the variation of $[OH^-]$ resulted from an interaction between water and cyclohexylamine. Sea-urchin-like and well-dispersed ZnO nanorods were prepared at low and high water content, respectively. Well-dispersed ZnO nanorods showed 1.8 fold change in resistance at 1 ppm $NO_2$ while there was no significant change in resistance at 50 ppm CO. This selective detection of $NO_2$ in the presence of CO can be used in automated car ventilation systems.

• Journal of Power System Engineering
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• v.14 no.6
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• pp.13-19
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• 2010

이 논문에서는 디젤자동차용 LNT와 SCR 촉매의 NO, $NH_3$ 흡착 및 탈리의 기본 특성과 수열화 온도와 시간 및 정량화된 황피독 농도에 대한 de-$NO_x$ 촉매의 내구성을 평가하였다. LNT 촉매는 열적으로 열화됨에 따라 Pt 및 Ba의 소결 및 응집으로 활성이 떨어져 $NO_x$ 전환율은 감소하였다. 반면에 Pt의 비활성화로 중간생성물인 $NH_3$ 생성량은 증가하였으며, 이때 생성된 $NH_3$는 LNT+SCR 복합시스템의 SCR 촉매의 환원제 역할을 담당한다. 1.0 g/L 이상의 황이 피독된 LNT 촉매는 탈황을 하여도 질소 산화물 흡장물질(Ba) 의 성능이 회복이 되지 않아 $NO_x$ 전환율은 회복되지 않았으며, 탈황 후 Pt 재활성화로 인해 NO2 및 SCR 환원제인 $NH_3$ 생성량은 증가하였다. SCR 촉매의 $NO_x$ 전환율은 $700^{\circ}C$ 36h, $800^{\circ}C$ 24h로 수열화 시킨 촉매는 전이금속 입자 성장 및 zeolite 구조 파괴로 인하여 급격하게 떨어졌으며, 0.36 g/L 황 피독된 촉매는 zeolite가 가지는 강산성 특정으로 내피독성이 강하여 탈황시 $NO_x$ 전환율은 회복되었다.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.77-77
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• 2008

• The Korean Journal of Applied Statistics
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• v.27 no.1
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• pp.115-122
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• 2014

A test for randomness of the binary random sequence is proposed in this paper. The proposed test statistic is based on the mean length of runs distributed with truncated geometric distribution and asymptotically ${\chi}^2_2$-distributed when the size of the sequences is large. A small Monte Carlo simulation compared the size of the test with a significant level as well as evaluated the test power. We applied the proposed method to the sequence of yes or no numbers in Lotto 6/45 and concluded that the randomness of Lotto is retained.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6C
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• pp.582-588
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• 2006

In this paper, the relationship among M-ary Sidel'nikov sequences generated by different primitive elements and decimation are studied. Their autocorrelation function and autocorrelation distribution are derived. It is proved that Sidel'nikov sequences for a given period are equivalent under the decimation, cyclic shift, and scalar multiplication of the sequence.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.57.1-57.1
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• 2009

나노이산화티타늄은 인체에는 화장품, 의약, 식품분야 등에 쓰이고 외부 환경 재료에는 광촉매로서 유독가스 정화제, 옥내 외 항균, 수소발생 가시광 응답형 촉매 및 멤브레인 필터 등과 전자소재용 유전재료, 발광 재료 등 용도가 다양하다. 나노 산화티타늄 화합물의 제조법은 수열합성법, 기상법 등 여러 방법이 있다. 이들에 대한 리뷰의 목적은 2009년도 정부의 투자 계획 중에서 본제목에 관련되는 핵심 산업 재원 원천기술 개발, 태양광, 풍력 등의 신재생 에너지 개발, 록색 기술 개발을 통한 에너지절약형 LED 개발, 차세대 핵심환경 기술 개발, 핵심나노기반기술개발 등의 개발을 위하여 4,363억 원의 예산을 편성하고 연구자와 기술자들이 참여하여 유익한 실적이 창출되기를 원하고 있으므로 본 발표자들은 이 분야에서 연구하는 연구자와 기술자들에게 이 분야에 관련되는 자료를 참고로 제시하는데 있다. 페로브스카이트형 산화물인 유전재료($BaTiO_3$), 발광재료(CaTiO3:Pr3+적색), 박막형 반응기재료($Ca0.8Sr0.2TiO_3$), 등의 여러 가지 산화물은 류통식 급속 승온 수열 합성법, 겔 졸 법, 수열 합성법 등 여러 방법에 의하여 페로브스카이트형 산화물 입자 직경이 약 20nm~100nm 범위까지 합성된다. 태양광을 조사하여 물을분해 해서 수소를 생산하는 산화티타늄계 가시광 응답형 Vis-$TiO_2$ 박막은 기상법으로 제조하는데 한 예로써 RF 스퍼터링법으로 박막을 제조하여 수소와 산소를 회수하였으며, 황도프산화티타늄, 질소 도프 산화티타늄은 유기물 분해에 의한 공해제거, $NO_x$ 제거 등 환경정화에 사용되고, 고온 고압수법/산화티타늄 복합기술에 의해서는 바이오매스 분해 하고, 일종의 수열법인 개량형 HyCOM 법은 가시광 응답성 산화티타늄을 합성하여 NO가스 제거에 사용한다. 이들 여러 방법에 관한 것을 소개하고저 한다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.2
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• pp.139-147
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• 1994

Orthophosphate crystals were grown by the hydrothermal method and the properties of grown crystals were investigated by means of X-ray diffraction. Vickers hardness tester, etc. The starting powders of $AIPO_4 and GaPO_4 $were prepared as a single phase by the solid state reaction of stoichiometric mixture of $AI_2O_3 or Ga_2O_3$ and $NH_4H_2PO_4$ and the subsequently by the hydrothermal treatment. The hydrothermal conditions for high growth rates of the orthophosphate crystals are as follows: $AlPO_4$ crystal; temperature ranges, between $170$~$200^{\circ}C$; temperatures difference, $15$~$20^{\circ}C;$, hydrothermal solvent, 4m HCl, $GaPO_4 crystal; temperature ranges, between $210 and 240^{\circ}C;$; temperature difference, $25$~$30^{\circ}C; $, hydrothermal solvent, 4m HCl. Morphologies of grown crystals tended to be bounded by (1010), (1011) and (0111) faces at low temperatures, and grew with well developed (0001) faces by increasing the growth temperature. On the other hand, the properties of orthophosphate crystals $(AlPO_4/GaPO_4)$ were as follows: lattice parameters (nm); a=0.494, c=1.094/a=0.490, c=1.105, density (gcm-3); 2.62/3.56, Vickers hardness (Nm^2); $1.02{\times}10^1^0/7.06{\times}10^9$, refractive indices; $ne=1.529{\pm}0.003, no=1.519{\pm}0.003/ne=1.611{\pm}0.006, no=1.599{\pm}0.006, birefringence; {\pm}0.01/{\pm}0.012$, dielectric constant (Fm-1); 6/7.